1. Field of the Invention
The present invention relates to a shaft behavior automatic measuring system capable of measuring a behavior of a shaft during a swing.
2. Description of the Related Art
As a method of measuring a behavior of a golf club shaft during a swing, a method using a strain gauge has been known. Japanese Laid-Open Patent Publication No. 11-178953 has disclosed a technique for sticking a strain gauge into a plurality of positions in a longitudinal direction of a shaft and measuring a behavior of the shaft based on strain data obtained from each of the strain gauges.
The strain gauge is connected to a wiring. The wiring disturbs a swing and remarkably interferes with the swing of a golf player. Due to the wiring, the golf player cannot carry out the swing as usual. Moreover, weights of a golf club and a shaft are increased depending on a weight of the strain gauge and the wiring. Because of the increase in the weights, the golf club and the shaft have different specifications from a state in which the strain gauge is not attached. The increase in the weight disturbs a normal swing of the golf player. The increase in the weight interferes with an original behavior of the golf club shaft.
As a method which does not use the strain gauge, it is possible to propose a method using a high speed camera. A mark is put in a plurality of positions in the longitudinal direction of the shaft and a behavior of the mark is analyzed based on an image photographed by means of the high speed camera. By providing a plurality of high speed cameras and photographing a swing on a plurality of points of view, it is possible to obtain a three-dimensional behavior of each mark. However, the method using the high speed camera requires a long time for an analysis. Moreover, the method using the high speed camera has poor precision in a measurement.